BaseX-Talk July 2010

basex-talk@mailman.uni-konstanz.de

26 participants
48 discussions

Feature Requests: Results
by Christian Grün 26 Jul '10

26 Jul '10

Dear all, some time ago I invited you to mail us your personal wish list for new, or revised, BaseX features. This mail serves as a little summary on the requests we've got so far, along with a short status report: QUERYING: - Support for XQuery 1.1 (most of all: group by): currently implemented, many features have already been finalized - More libraries: additional modules for file operations, http requests, etc. (based on EXPath, etc.): in progress - XSLT Transformations: Andy C. kindly offered some support! DATABASE: - Collections functions: commands for adding/deleting documents have been revised in the latest version; feedback is welcome! - Backups: currently implemented - Database triggers: design in progress - Schema validation: won't be included that soon, as BaseX works (and will stay) schema oblivious - Retaining CData: not intended by the specs; instead, serialization parameters should be used… TRANSACTIONS: - Rollbacks: future work, but will definitely be implemented - Multiple writers: will be supported at least on database or document level - Index Updates: design in progress INTERFACES: - Communication with relational databases: existing standards/solutions might be investigated first to stay conformant, and support as many databases as possible (suggestions?) - XQJ: Improved binding of Java types (might require XML schema support to be properly implemented) GUI: - XQuery Editor: syntax-based highlighting, code completion: design in progress GENERAL: - Commmercial support: on the way - Full Documentation: always in progress, but edged out by other todos… - Installer for Windows version: currently implemented - Service/Daemon: already implemented (BaseX server can be run as service via -s); installer might include Windows Service Thanks again for your contributions; please remember us if I've forgotten something. We'll keep you informed – and you can be sure that we'll always keep BaseX as light-weight as possible. Christian ___________________________ Christian Grün University of Konstanz Department of Computer & Information Science D-78457 Konstanz, Germany Tel: +49-7531-88-4449, Fax: +49-7531-88-3577 http://www.inf.uni-konstanz.de/~gruen

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support for line/column numbers when errors occur
by Godmar Back 26 Jul '10

26 Jul '10

When debugging complex XQuery expressions, we frequently encounter errors such as these [XPTY0004] Invalid cast from empty-sequence to string: () when an XPath expression evaluates to an empty sequence. When using BaseX's XQJ implementation, the line and column number fields of the corresponding XQQueryException are both 0. This lack of pinpointed information makes debugging the Xquery expression time consuming. It would be tremendously helpful if the exception contained more information about the source of the empty sequence that's causing the XPTY0004 error. Also, if I weren't to use BaseX's XQJ implementation, would I be receiving more helpful error messages? - Godmar

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BaseX adds bogus duplicate default namespace prefixes when inserting nodes
by Godmar Back 26 Jul '10

26 Jul '10

To follow up on my previous email, we observe the following. We run a query: declare namespace libx='http://libx.org/xml/libx2'; declare namespace atom='http://www.w3.org/2005/Atom'; declare variable $entry as xs:anyAtomicType external; declare variable $id as xs:string external; declare variable $feed as xs:anyAtomicType := doc('libx2_feed')/atom:feed; delete node $feed/atom:entry[atom:id=$id], (: INVESTIGATE: this results in wrong xmlns entries :) *insert node $entry into $feed* whereby we bind 'entry' to a DOM node using the org.w3c. Implementation. When we print the about-to-be-inserted entry from Java code prior to insertion, we see: <?xml version="1.0" encoding="UTF-8"?><entry xmlns=" http://www.w3.org/2005/Atom" xmlns:libx="http://libx.org/xml/libx2"> <id>3</id> (rest omitted) If we run a database dump via the org.basex.BaseX program (query: doc('libx2_feed')) right after the update, we see this: <entry xmlns="" xmlns="http://www.w3.org/2005/Atom" xmlns:libx=" http://libx.org/xml/libx2"> <id>3</id> <title> (rest omitted) Other than the spurious 'xmlns=""', the rest looks ok. It seems to me that BaseX should never allow two default namespace prefixes for any element. - Godmar

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Bea Sancho te ha invitado a Tuenti
by tuenti.com 26 Jul '10

26 Jul '10

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BASEX and PHP: for $node in doc("factbook") -- ERROR: Unknow
by johanna.vompras＠uni-bielefeld.de 26 Jul '10

26 Jul '10

Hi all! I have written some PHP Scrips with test queries to the factbook database, which are are well executed at my local machine (Windows, XAMPP, BaseX on localhost, Port 1984). Now, I have ported my examples to a remote server, and it seams that the query string is not accepted. For example: The query (for $node in doc("allbus")//(d:QuestionItem|d:MultipleQuestionItem) return data($node/@id)') results in the following error: Unknown command 'for'; try "help". Other queries result in Error: 0 instead of 1 commands received. We have BaseX Client running and the queries can be submitted through the linux console (> xquery for $node in doc("factbook")//country return $node). Opening the database and querying also works. But from my PHP scripts it does not work. Does anybody know went wrong with my installation? Here is the example: <?php include('BaseXClient.php'); //set content-type header header('Content-type: application/json'); // commands to be performed $namespaces = 'declare namespace d="ddi:datacollection:3_0";'; $cmd = 'for $node in doc("allbus")//(d:QuestionItem|d:MultipleQuestionItem) return data($node/@id)'; $cmd2 = 'for $node in doc("allbus") //(d:QuestionItem|d:MultipleQuestionItem)/d:QuestionText/d:LiteralText/d:Text return data($node)'; try { // create session $session = new Session("129.......", 9000, "admin", "admin"); //create JSON data structure $startJsonObject = "{ questions: ["; $endJsonObject = "]}"; try { $query = $session->query($namespaces.$cmd); $query2 = $session->query($namespaces.$cmd2); $counter = 0; while($query->more()) { $next = $query->next(); $query2->more(); $next2 = $query2->next(); $counter++; ................ etc... ?>

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BaseX XML interface
by NewIntellectual 24 Jul '10

24 Jul '10

Godmar Back asks: I'm still curious what XML interface I'm missing. While I agree that published interfaces should work properly, I think a simple point is being completely missed. Both XML and XQuery are, by their nature, human readable text, regardless of their complexity. That means that queries can be sent simply as text strings, and results of any size can also be returned in that way and then parsed as XML fragments in any number of myriad ways, including parsing to an in-memory DOM. I successfully use this approach to query an XML database representing close to 200,000 pages of text and to retrieve pretty large XML fragments (actually documents with a single root element) quickly. This may be a simple approach but there is no loss of generality by using it - in other words, using a more complex interface will not let you do some XQuery processing that cannot be done with this approach. You can use the following code to access BaseX for example (in this case to a local server using default permissions). I am prefixing text to make the result string an XML document but your code may not need it: package [...]; import java.io.*; import java.util.*; import org.basex.server.ClientSession; public class QueryText { public String doQuery(String xquery) { ClientSession session; String result; ByteArrayOutputStream buffer = new ByteArrayOutputStream(); session=null; result="NO RESULT"; try { session = new ClientSession("localhost", 1984, "admin", "admin"); session.execute(xquery, buffer); result="<?xml version='1.0' encoding='UTF-8'?>"+buffer.toString("UTF-8"); } catch(Exception e) { ... } finally { try { session.close(); } catch(Exception e) { ... } } } }

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Addendum to last post
by NewIntellectual 23 Jul '10

23 Jul '10

The code I posted accidentally omitted a critical step - add a 'return result;' as the last statement in the doQuery method.

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working with XML databases (BaseX) in Java
by Godmar Back 23 Jul '10

23 Jul '10

Hi, I'd like to follow up for the benefit of the list on this comment by Christian: > As mentioned, our DOM interfaces haven't been tested very much, but > your focus on DOM and XQJ might inspire other users to play around > with this interface as well, and give us more feedback. Could people share their approaches to working with XML in Java? My (apparently outdated) knowledge is that only two approaches are in wide use: those that use an in-memory representation of an XML document (or fragment) - e.g., either XOM, org.w3c.'s DOM, JDOM, etc. or approaches that use a stream-based approach (SAX). Naively, I would have expected that XML databases such as BaseX would provide excellent support for at least one of the widely used DOM interfaces. (In fact, Christian made an earlier comment that BaseX uses an "optimized" (albeit incomplete) implementation of org.w3c.'s DOM classes.) Are there other existing approaches besides DOM that would allow me to retrieve and update XML documents, and represent portions of them in memory? - Godmar

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Re: [basex-talk] How to start BaseX server windows from the command line?
by Andreas Weiler 16 Jul '10

16 Jul '10

Hi Nigel, > 2. Is there a way I can close the command prompt window but leave BaseX > server running as a process in the background? there is no option in windows like the nohup option in linux which puts the commands in background. So you have to create a service with the basex startup on your machine and start this. Another way is to start it like this: start /B java -cp basex.jar org.basex.BaseXServer this will let you get back to the command line (with enter). But when you close the console the server is closed too. Another way is to install cygwin (http://www.cygwin.com/) and run it like on a linux machine: nohup java -cp basex.jar org.basex.BaseXServer & Kind regards, Andreas Nigel Alderton schrieb: > Thanks very much. That worked. > > But unfortunately it doesn't return to the command line prompt, and if I > manually close the command window, the BaseX server stops. > > 1. Is this behaviour intentional? > 2. Is there a way I can close the command prompt window but leave BaseX > server running as a process in the background? > > Thanks again. Sorry to bother you with such newbie questions! > > Nigel > > -----Original Message----- > From: Andreas Weiler [mailto:andreas.weiler@uni-konstanz.de] > Sent: 16 July 2010 11:48 > To: Nigel Alderton > Cc: basex-talk > Subject: Re: [basex-talk] How to start BaseX server windows from the command > line? > > Dear Nigel, > > yes you need to download the basex.jar file. > Then you have to execute: java -cp BaseX61.jar org.basex.BaseXServer > > See for more information: http://www.inf.uni-konstanz.de/dbis/basex/server > > I hope this helps. > > Kind regards, > Andreas > > Nigel Alderton schrieb: > >> Thanks Andreas, I tried that but an error appeared: >> >> C:\Program Files\BaseX>java -cp basex.jar org.basex.BaseXServer >> Exception in thread "main" java.lang.NoClassDefFoundError: >> org/basex/BaseXServer >> Caused by: java.lang.ClassNotFoundException: org.basex.BaseXServer >> at java.net.URLClassLoader$1.run(Unknown Source) >> at java.security.AccessController.doPrivileged(Native Method) >> at java.net.URLClassLoader.findClass(Unknown Source) >> at java.lang.ClassLoader.loadClass(Unknown Source) >> at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) >> at java.lang.ClassLoader.loadClass(Unknown Source) >> Could not find the main class: org.basex.BaseXServer. Program will exit. >> >> I only have one file: BaseX.exe in c:\program files\BaseX. Do I need to >> download basex.jar to get the standalone server version of BaseX? >> >> Is there any online documentation regarding configuring an running BaseX >> > on > >> windows? >> >> Nigel >> >> -----Original Message----- >> From: Andreas Weiler [mailto:andreas.weiler@uni-konstanz.de] >> Sent: 16 July 2010 11:32 >> To: Nigel Alderton >> Cc: basex-talk(a)mailman.uni-konstanz.de >> Subject: Re: [basex-talk] How to start BaseX server windows from the >> > command > >> line? >> >> Dear Nigel, >> >> just start it with: java -cp basex.jar org.basex.BaseXServer >> >> Kind regards, >> Andreas >> >> Nigel Alderton schrieb: >> >> >>> Hi, >>> >>> How can I start the windows version of the BaseX server from the >>> command line ie. **without** using the client user interface File - >>> Server Administration - Start? >>> >>> I want to configure BaseX server to start when my PC starts? Can this >>> be done, if so how? >>> >>> I have BaseX Version 6.1. >>> >>> Thanks, >>> >>> Nigel >>> >>> ------------------------------------------------------------------------ >>> >>> _______________________________________________ >>> BaseX-Talk mailing list >>> BaseX-Talk(a)mailman.uni-konstanz.de >>> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk >>> >>> >>> >> >> > >

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Re: [basex-talk] How to start BaseX server windows from the command line?
by Andreas Weiler 16 Jul '10

16 Jul '10

Dear Nigel, yes you need to download the basex.jar file. Then you have to execute: java -cp BaseX61.jar org.basex.BaseXServer See for more information: http://www.inf.uni-konstanz.de/dbis/basex/server I hope this helps. Kind regards, Andreas Nigel Alderton schrieb: > Thanks Andreas, I tried that but an error appeared: > > C:\Program Files\BaseX>java -cp basex.jar org.basex.BaseXServer > Exception in thread "main" java.lang.NoClassDefFoundError: > org/basex/BaseXServer > Caused by: java.lang.ClassNotFoundException: org.basex.BaseXServer > at java.net.URLClassLoader$1.run(Unknown Source) > at java.security.AccessController.doPrivileged(Native Method) > at java.net.URLClassLoader.findClass(Unknown Source) > at java.lang.ClassLoader.loadClass(Unknown Source) > at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) > at java.lang.ClassLoader.loadClass(Unknown Source) > Could not find the main class: org.basex.BaseXServer. Program will exit. > > I only have one file: BaseX.exe in c:\program files\BaseX. Do I need to > download basex.jar to get the standalone server version of BaseX? > > Is there any online documentation regarding configuring an running BaseX on > windows? > > Nigel > > -----Original Message----- > From: Andreas Weiler [mailto:andreas.weiler@uni-konstanz.de] > Sent: 16 July 2010 11:32 > To: Nigel Alderton > Cc: basex-talk(a)mailman.uni-konstanz.de > Subject: Re: [basex-talk] How to start BaseX server windows from the command > line? > > Dear Nigel, > > just start it with: java -cp basex.jar org.basex.BaseXServer > > Kind regards, > Andreas > > Nigel Alderton schrieb: > >> Hi, >> >> How can I start the windows version of the BaseX server from the >> command line ie. **without** using the client user interface File - >> Server Administration - Start? >> >> I want to configure BaseX server to start when my PC starts? Can this >> be done, if so how? >> >> I have BaseX Version 6.1. >> >> Thanks, >> >> Nigel >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> BaseX-Talk mailing list >> BaseX-Talk(a)mailman.uni-konstanz.de >> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk >> >> > >

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BaseX-Talk July 2010